Histone deacetylase inhibitors trichostatin A and valproic acid circumvent apoptosis in human leukemic cells expressing the RUNX1 chimera

• Published in: Cancer science Vol. 99; no. 2; pp. 414 - 422
• Main Authors: Sasaki, Ko, Yamagata, Tetsuya, Mitani, Kinuko
• Format: Journal Article
• Language: English
• Published: Melbourne, Australia Blackwell Publishing Asia 01.02.2008; Blackwell
• Subjects: Acetylation; Antineoplastic Agents - pharmacology; Apoptosis - physiology; Biological and medical sciences; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Core Binding Factor Alpha 2 Subunit - genetics; Core Binding Factor Alpha 2 Subunit - metabolism; Enzyme Inhibitors - pharmacology; Hematologic and hematopoietic diseases; Histone Deacetylase Inhibitors; Histone Deacetylases - metabolism; Humans; Hydroxamic Acids - pharmacology; K562 Cells; Leukemia - genetics; Leukemia - metabolism; Leukemias. Malignant lymphomas. Malignant reticulosis. Myelofibrosis; Medical sciences; Mutant Chimeric Proteins - metabolism; Original; Tumors; Valproic Acid - pharmacology; Human; 4-Aminobutyrate transaminase; Enzyme; Transferases; Leukemia; Enzyme inhibitor; Malignant hemopathy; Valproic acid; Histone deacetylase inhibitor; Cancerology; Cell death; Transaminases; Chimerism; Cancer; Apoptosis; Chimera
• ISSN: 1347-9032; 1349-7006; 1349-7006
• DOI: 10.1111/j.1349-7006.2007.00699.x

Disturbance of the normal functions of wild‐type RUNX1 resulting from chromosomal translocations or gene mutations is one of the major molecular mechanisms in human leukemogenesis. RUNX1‐related chimeras generated by the chromosomal translocations repress transcriptional activity of wild‐type RUNX1 by recruiting the co‐repressor/histone deacetylase complex. Thus, histone deacetylase inhibitors are expected to restore normal functions of wild‐type RUNX1 and thereby affect the growth and differentiation ability of leukemic cells expressing the chimera. We investigated the in vitro effects of histone deacetylase inhibitors, trichostatin A and valproic acid, on human leukemic cell lines such as SKNO‐1 and Kasumi‐1 expressing RUNX1/ETO, Reh expressing TEL/RUNX1 and SKH‐1 co‐expressing RUNX1/EVI1 and BCR/ABL. We also employed K562 cells expressing BCR/ABL without such a chimera as a control. Treatment with each inhibitor increased acetylated histone 4 in all of these cell lines. Interestingly, proliferation of SKNO‐1, Kasumi‐1, SKH‐1 and Reh cells was significantly suppressed after 3‐day culture with trichostatin A or valproic acid, when compared to that of K562 cells. We observed cell cycle arrest and apoptotic induction in the RUNX1 chimera‐expressing cells by the propidium iodide staining. Up‐ and downregulation of cell cycle regulator genes appeared to be the molecular basis for the former, and activation of both extrinsic and intrinsic apoptotic caspases for the latter. We propose histone deacetylase inhibitors to be an attractive choice in the molecular targeting therapy of RUNX1‐related leukemia. (Cancer Sci 2008; 99: 414–422)